University of Waterloo

About: University of Waterloo is a education organization based out in Waterloo, Ontario, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 36093 authors who have published 93906 publications receiving 2948139 citations. The organization is also known as: UW & uwaterloo.

Monitoring surgical performance using risk-adjusted cumulative sum charts

Abstract: The cumulative sum (CUSUM) procedure is a graphical method that is widely used for quality monitoring in industrial settings. More recently it has been used to monitor surgical outcomes whereby it 'signals' if sufficient evidence has accumulated that there has been a change in the surgical failure rate. A limitation of the standard CUSUM procedure in this context is that since it is simply based on the observed surgical outcomes, it may signal as a result of changes in the referral pattern, such as an increased proportion of high-risk patients, rather than due to a change in the actual surgical performance. We describe a new CUSUM procedure that adjusts for each patient's pre-operative risk of surgical failure through the use of a likelihood-based scoring method. The procedure is therefore ideally suited for settings where there is a variable mix of patients over time.

Adapting the RUSLE to model soil erosion potential in a mountainous tropical watershed

Abstract: This research integrates the Revised Universal Soil Loss Equation (RUSLE) with a Geographic Information System (GIS) to model erosion potential for soil conservation planning within the Sierra de Manantlan Biosphere Reserve (SMBR), Mexico. Mountainous topography and a tropical uni-modal precipitation regime characterize this region. These unique climatic and topographic characteristics required a modification of the standard RUSLE factors and their derivation. The resulting RUSLE–GIS model provides a robust soil conservation planning tool readily transferable and accessible to other land managers in similar environments. Future pressure to expand agriculture and grazing operations within the SMBR will unquestionably accentuate the already high rate of soil erosion and resultant sediment loading of watercourses occurring in this region. Until recently there did not exist a reliable or financially viable means to model and map soil erosion within large remote areas. An increase in the reliability and resolution of remote sensing techniques, modifications and advancements in watershed scale soil erosion modelling techniques, and advances in GIS, represent significantly improved tools that can be applied to both monitoring and modelling the effects of land use on soil erosion potential. Data used in this study to generate the RUSLE variables include a Landsat Thematic Mapper image (land cover), digitized topographic and soil maps, and tabular precipitation data. Soil erosion potential was modelled within Zenzontla, a sub-catchment of the Rio Ayuquila, located in the SMBR, and the results are presented as geo-referenced maps for each of the wet and dry precipitation seasons. These maps confirm that high and extreme areas of soil loss occur within the Zenzontla sub-catchment, and that erosion potential differs significantly between wet and dry seasons.

Low back stability: from formal description to issues for performance and rehabilitation.

Abstract: Low back stability: from formal description to issues for performance and rehabilitation. Exerc. Sport Sci. Rev. Vol. 29, No. 1, pp. 26-31, 2001. The concept of stability, together with notions of design and the application of stabilization exercise, is briefly synthesized. The objective is to challenge muscle systems to achieve sufficient functional stability but in a way that spares the spine of excessive exacerbating load.

Frank's family of bivariate distributions

Abstract: SUMMARY This paper examines the properties of a new class of bivariate distributions whose members are stochastically ordered and likelihood ratio dependent The proposed class can be used to construct bivariate families of distributions whose marginals are arbitrary and which include the Frechet bounds as well as the distribution corresponding to independent variables Three nonparametric estimators of the association parameter are suggested and Monte Carlo experiments are used to compare their small-sample behaviour to that of the maximum likelihood estimate

On the predictive validity of attitudes: The roles of direct experience and confidence1

Abstract: Previous research has demonstrated that behavior is more accurately predicted from attitudes formed via direct, behavioral interaction with the attitude object than from attitudes developed via indirect, nonbehavioral experience. The present research examined the hypothesis that the confidence with which an attitude is held may be a mediating variable in the observed relationship between the manner of attitude formation and attitude-behavior consistency. In the first experiment, it was demonstrated that subjects who formed their attitudes through direct experience held those attitudes more confidently and behaved more consistently with those attitudes than did subjects who formed their attitudes through indirect experience. In the second experiment, it was found that, regardless of the manner of attitude formation, subjects who were led to believe that they held their attitudes confidently displayed greater attitude-behavior consistency than did subjects led to believe that they held their attitudes with little confidence. Taken together, the results suggest that it may be fruitful to view confidence both as a variable which mediates the effect of the manner of attitude formation on attitude-behavior consistency and as one which, independent of how an attitude is formed, acts as a determinant of attitude-behavior consistency.